1. Field of the Invention
This invention generally relates to electrodes useful in electrochemical cells and, more particularly, this invention relates to reinforced composites of reactive metals useful as electrodes in electrochemical cells.
2. Description of the Prior Art
Electrochemical cells utilizing reactive metal electrodes are well known. See, for example, Rowley U.S. Pat. No. 3,791,871 issued Feb. 12, 1974, wherein a cell using an aqueous electrolyte, an anode of an alkali metal, such as lithium, for example, and a cathode spaced from the anode is disclosed.
In such prior cells, the electrolyte may be aqueous or non-aqueous, and the cathode may comprise an electrochemically active or passive metal, such as silver oxide or iron, respectively, or a gas consuming electrode, such as an air cathode, for example. All such cells are characterized, however, by an electrochemical reaction which occurs between the reactive metal of the anode (or cathode) and the electrolyte, whereby the reactive metal is consumed.
As a result of the electrochemical reaction and the consequent consumption of reactive metal, the surface of the reactive metal electrode is eroded during operation of the cell.
Since the production of electrochemical energy depends directly upon the rate of reaction of the reactive metal with the electrolyte, it is important to promote turbulence at the surface of the reactive metal electrode in order to maximize the rate of reaction by carrying away products of reaction and providing fresh electrolyte to unreacted metal.
Some prior reactive metal cells have utilized rigid screens or open cell or reticulated polymer foam as inter-electrode separators in order to promote turbulence. However, the initial inter-electrode gap is generally fixed and, as the consumable metal electrode erodes, the gap widens and the turbulence promoting effect of such separators is decreased.
As an electrode is eroded during operation and the inter-electrode gap increases, the electrode sensitivity to shock and vibration may increase due to the decreased support which results from the widening of the inter-electrode gap.
Storage problems may occur in prior cells utilizing polymer foam as inter-electrode spacers where the foam is stored in the cell in a compressed state. If stored over a period of years, such foam can lose its resilience and thus its ability to expand to fill the inter-electrode gap during subsequent operation. As a result, deleterious electrolyte flow-by may be experienced.
The use of multicell power modules comprising many electrode pairs is well known. The assembly of such modules is complicated by the use of discrete individual foam separator layers as inter-electrode spacers.